Fingerprints are well understood to be unique to an individual and are therefore useful for identification and verification purposes. The surface asperities (that is, the ridges and valleys) that constitute a fingerprint can be sensed and imaged in a variety of ways and used thereafter to compare with previously stored fingerprint information for these purposes.
A fingerprint offers a reliable and inexpensive means of authenticating an individual's identity. Thus, fingerprint identification systems have played a critical role in modern society in both civil and criminal applications. For example, criminal identification in public safety sectors is an integral part of any present day investigation. Similarly in civil applications such as credit card or personal identity fraud, fingerprint identification has become an essential part of the security process.
One known application for fingerprint identification and authentication is in association with a smartcard. In such an application, a fingerprint authentication module is embedded in a smartcard. The fingerprint authentication module is typically a set of self-contained integrated circuit (“IC”) chips that comprise all elements necessary for: performing an enrollment algorithm for a user for capturing, enrolling and storing an initial fingerprint image against which other fingerprints will be verified; capturing a subsequent fingerprint image for use in the verification stage; and performing an algorithm for comparison with the stored fingerprint image and user authentication. Thus, the fingerprint module typically includes a sensor device, a processing device and a memory device. Once the fingerprint of the authorized user has been verified, a separate smartcard IC chip, also embedded in the smartcard, may be automatically activated to proceed and establish communications with a host system.
The above-described smartcards with embedded fingerprint authentication systems have a number of limitations. For instance, the fingerprint authentication module is a completely separate set of IC chips from the smartcard chip. This increases the cost of the smartcard since separate pieces of silicon must be used for each IC chip. This also increases the power consumption of the smartcard due to the separated IC chips.
Another limitation of these smartcards having fingerprint authentication is that the two IC chips are typically located on opposite ends of the smartcard. Accordingly in an application where the smartcard IC establishes communications with the host device via a contact-less means such as, for instance, radio frequency communication, the circuitry needed to connect the two chips typically limits the area available for an antenna at the desirable frequency and with sufficient gain so that the smartcard may be positioned an adequate distance from a reader device and still retain operability.
Another limitation of two separate chips, one for smart card functions and one for sensor functions, is that there is a physical interconnection path between the two which is subject to security violations. For example, inserting another person's fingerprint into the system.
Yet another limitation is that the sensor on the fingerprint authentication chip is typically capacitance based. Capacitance based mechanisms offer relatively good asperity detection but are susceptible to electrostatic discharge that can impair or destroy the mechanism. Many such mechanisms must utilize titanium nitride materials to protect against such electrostatic discharge and this complicates manufacturability. Furthermore, such capacitance based mechanisms typically require a considerable amount of processing capability to convert the sensed asperities into storable data. In addition to the limitations of capacitance based sensors in capturing a fingerprint, there are limitations in the ability to integrate capacitive based sensors with a smart card. For example, capacitive sensors require operational amplifiers for processing that are not normally contained within a smart card IC. Addition of these devices would substantially increase the cost, size, and power consumption of the smart card IC.
A need therefore exists for a cost-effective smartcard having fingerprint authentication capabilities, which does not require separate smartcard and fingerprint authentication IC chips. It is further desired that the smartcard have suitable and cost-effective means for protecting itself against electrostatic discharge.